Cherry rootstock--cob variety

ABSTRACT

The invention relates to a new and distinct variety of cherry tree useful as a cherry rootstock for supporting ornamental flowering cherry cultivars. The new variety originated as a seedling by crossing Prunus avium L. F299/2 and Prunus pseudocerasus Lind. It has been found that ornamental cherry cultivars, and in particular Yukon, grow more vigorously on the new variety during the first six years than on Prunus avium F12/1 and various inter- and intra-specific hybrids. THe resulting thick trunk formation and the resulting precocious formation of blossoms by the ornamental cherry cultivar are particularly appealing to nurserymen.

SUMMARY OF THE INVENTION

The original plant was Seedling No. 17 in a family of sterile hybridseedlings, Fb 2/58, originally produced during 1958 by crossing Prunusavium L. F299/2 and Prunus pseudocerasus Lind. The Colt dwarfing cherryrootstock (U.S. Plant Pat. No. 4,059) was a member of this same familyof seedlings. Following evaluation and testing the new variety of thepresent invention was found to be useful as an improved cherry rootstockfor supporting ornamental flowering cherry cultivars. The pollination,evaluation, and testing were carried out at the East Malling ResearchStation, Maidstone, Kent, England.

At the present time there is considerable demand for ornamentalflowering cherry cultivars. The present variety finds utility as animproved rootstock for use with such ornamental flowering cherrycultivars. More specifically, it has been found that ornamentalflowering cherry cultivars such as Yukon grow considerably morevigorously on the rootstock of the present invention particularly duringthe first six years than on Prunus avium F12/1 and various inter- andintra-specific hybrids commonly employed. The increased vigor ismanifest in part by a thicker trunk and the more precocious formation ofblossoms by the ornamental cherry cultivar. As will be readilyrecognized by nurserymen, such characteristics are of major economicsignificance in the horticulture industry.

The cherry rootstock of the present invention has been designated theCob variety.

Cherry trees of the Cob variety may be easily propagated by hardwood andsoftwood cuttings. Such asexual reproductions at the East MallingResearch Station have demonstrated that the distinctive characteristicsare stable and are transmitted without change through succeedingpropagations.

BRIEF DESCRIPTION OF THE PHOTOGRAPHS

The accompanying photographs show typical specimens of the improvedcherry rootstock of the present invention, while growing duringSeptember 1981 at the East Malling Research Station, wherein:

FIG. 1 is a hedge of Cob cherry rootstock planted during 1978 with theheight being indicated in centimeters,

FIG. 2 is a closer view of a portion of the same hedge shown in FIG. 1,

FIG. 3 is a one year old vegetative shoot of the Cob cherry rootstock,

FIG. 4 is a leaf of the Cob cherry rootstock with the dimensions beingindicated in centimeters, and

FIG. 5 illustrates pre-formed root initials appearing at the base of aone year old shoot of the Cob cherry rootstock.

DETAILED DESCRIPTION

The following is a detailed description of the new cherry rootstock'ssummer characteristics as observed on one year old shoots produced onhedges in the propagation nursery at the East Malling Research Station,Kent, England.

The colors of the leaves and shoots vary with the growing conditions andgenerally are not considered to be of value in identifying therootstock. In those instances where a color assessment has been madereference is to Munsell Color Charts for Plant Tissues, 1st Edition(1952), Munsell Color Co., Inc., Baltimore, Md., U.S.A. In otherinstances general color terms are used in accordance with their ordinarydictionary significance.

Asexual reproduction of the new Cob variety by hardwood and softwoodcuttings, as performed at the East Malling Research Station, shows thatthe described characteristics and distinctions come true to form and aretransmitted through succeeding propagations.

The new variety exhibits erect sturdy shoots up to 80 cm. in length withbright clean green leaves which are slightly upturned with smallbranched feathery stipules on younger leaf petioles. The tips of thegrowing shoots are pinkish.

The stems are green with a silvery-white waxy covering on older parts.The lenticels are few and irregularly round in shape. They are whitishin coloration when young and turn to a bright rusty color with age. Inhedges which are two years old or more at the end of the growing season,preformed root initials are found on the base of many shoots.

General habit:

Strength of growth.--Sturdy shoots of moderate vigor with particularlyshort internodes.

Habit of growth.--Erect, stiff and compact.

Number of laterals on previous growth.--Not observed on one-year shoots.

Feathering on current growth.--Often feathered, both from base and upperpart of shoot.

Number of shoots on hedge.--Moderate.

Wood: Summer.

Color.--Green when young (Munsell 2.5 GY 6/4), as it matures asilver-white waxy covering develops in places (Munsell 2.5 GY 6/2).

Hairiness.--Few short hairs visible with lens. Appears smooth to unaidedeye.

Texture.--Ridged below leaf attachments, otherwise fairly smooth.

Lenticels:

Number.--Not many.

Conspicuousness.--Summer conspicuous.

Shape.--Roundish to irregular.

Color.--Whitish, turning to corky orange brown (Munsell 7.5 YR 6/10).

Distribution.--Scattered.

Size.--Medium.

Leaves:

Size.--Moderately large, length approximately 118 mm., breadthapproximately 57 mm.

Shape.--Elliptic.

Base.--Obtuse, attenuated.

Apex.--Acuminate.

Serrations.--Doubly serrate.

Upper surface.--Flat, shiny, veins sunken with tiny hairs visible underlens.

Margin.--Raised slightly, wavy.

Pose in relation to stem.--Slightly upturned.

Color.--Clear green (Munsell 5 GY 4/6).

Hairiness on under surface.--Few hairs on veins visible under lens.

Texture.--Upper surface smooth, lower surface rougher.

Color of tips of shoots.--Pale and pinkish when actively growing, greenwhen growing has ceased.

Petiole:

Shape.--Channelled.

Length.--Medium length, approximately 17 mm.

Color.--Mainly green with brown-red tinges.

Pose.--Upturned.

Glands.--One or two, sometimes opposite, at or just below leaf junction.

Stipules (not always present):

Size.--Moderate, branched.

Margin.--Parted.

Shape.--Feathery.

Pose.--Erect.

Buds:

Size.--Small.

Shape.--Pear shaped.

Compactness.--Neat, bud scales overlapping.

Color.--When young green with pink tinges to edge of bud scales. Older,a brownish-red color.

Hairiness.--Not hairy.

Pose.--Almost upright, but separate from shoot.

Base.--Very slightly extended.

General characteristics:

Suckering.--Low.

Yield potential.--Not applicable for ornamental cultivars.

Compatibility.--Tests to date indicate no problems.

Stem girth.--Rapid increase in girth which is an important criterion forornamental trees.

Blossom potential.--Rapid early shoot growth produces a large blossombearing surface.

I claim:
 1. A new and distinct variety of cherry tree useful as animproved rootstock for ornamental flowering cherry cultivars,substantially as illustrated and described, which when used as suchrootstock facilitates more vigorous growth, enhanced blossom formation,and thicker trunk growth during the first six years.